Chapter 9 |
POST-PROCESSING: GENERAL TECHNIQUES |
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Calculating Apparent Heat Release |
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PNG buttons in the Graph Tool.
Calculating Apparent Heat Release
This section describes the process of obtaining an apparent heat release plot from cylinder pressure data using the es-ice post-processing tools.
The engine quantities within the Operations panel are taken from data in the es-ice.pos file. Note that these are specified in metres, as opposed to model units. Using this units system ensures that the calculated results are presented in standard form. The Gamma for gas property can be adjusted depending on user requirements. However, its default value is suitable for this tutorial.
To calculate the apparent heat release:
•Deselect the toggle button next to items 258 and 259 to clear the curtain flux data from the graph display
•Locate item 9 in the list labelled
Pressure: region 1
•Click Operations and then click Pressure: region 1 to perform an operation on the pressure data
•In the Operations panel, accept the defaults and click Create plot data
•Close the Operations panel
The previous steps add the AHR: Pressure: region 1 plot data to the list. To plot the apparent heat release:
•Select the AHR: Pressure 1: region 1 data
•Click Plot
•Set the Range to -20 and 60 to cover a more suitable data range
•Set the number of lines to 8
•Set Label to Apparent Heat Release
When complete, the panel appears as shown in Figure 9-3.
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POST-PROCESSING: GENERAL TECHNIQUES |
Chapter 9 |
Plotting an Indicator Diagram |
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Figure 9-3 Apparent heat release plot
Plotting an Indicator Diagram
The following section describes the creation of a plot showing pressure against volume (also known as an indicator diagram). This process involves exporting es-ice.pos results to XY-type files and then reading relevant data from the required file back into es-ice.
Begin by deleting all es-ice.pos plot data from the Graph Tool
•In the Graph Tool, click Delete
•Answer Yes to the prompt in the main es-ice panel
Next, write the XY file:
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Chapter 9 |
POST-PROCESSING: GENERAL TECHNIQUES |
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Plotting an Indicator Diagram |
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• Enter the following command in the main es-ice panel: |
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Graph, Write, Full, es-ice.pos, ! |
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Numerous XY files are written into your current working directory but only the |
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Cyl1 file is required for this example. Note that all comment lines within the files |
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are preceded by a "!", as specified in the above command. |
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• Open file Cyl1 with a text editor. The first part of the file provides a |
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summary of its contents. As shown in Figure 9-4, columns 7 and 9 contain |
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volume and pressure data and these are required in this example. |
Figure 9-4 Cyl1 file summary
Figure 9-5 shows the remainder of the file, which contains solution data in column format
Figure 9-5 Cyl1 file contents
File Cyl1 is now read into es-ice and a column is chosen for the X-axis data.
•Enter the following command in the es-ice command window:
Graph, Read, Cyl1, XYfile, !, 7
This reads file data into the Graph Tool, with column 7 (volume) used for the x-axis values. To plot cylinder pressure against volume:
•In the Graph Tool, select item 8 in the list, labelled Column 9
•Click Plot
•Set the Domain minimum and maximum values to 0 and 0.00025 to cover a more suitable data range
•Set the number of lines to 10
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Chapter 9 |
Calculating Global Engine Quantities |
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•Set the Label to Volume
•Change the Range minimum and maximum values to 0 and 7e+06
•Set the number of lines to 7
•Set the Label to Pressure
When complete, the panel will appear as shown in Figure 9-6.
Figure 9-6 Indicator diagram
Calculating Global Engine Quantities
This section describes the acquisition of global engine quantities from data in the es-ice.pos file. The quantities are net indicated work, power, and indicated mean effective pressure.
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